const webpack = require('webpack');
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const fs = require('fs');
const srcRoot = path.resolve(__dirname, 'src');
const devPath = path.resolve(__dirname, 'dev');
const pageDir = path.resolve(srcRoot, 'page');
const mainFile = 'index.js';

function getHtmlArray (entryMap) {
  let htmlArray = [];
  Object.keys(entryMap).forEach((key) => {
    let fullPathName = path.resolve(pageDir, key);
    let fileName = path.resolve(fullPathName, key + '.html');

    if (fs.existsSync(fileName)) {
      htmlArray.push(new HtmlWebpackPlugin({
        filename: key + '.html',
        template: fileName,
        chunks: ['common', key]
      }));
    }


  });
  return htmlArray;
}

function getEntry () {
  let entryMap = {};

  fs.readdirSync(pageDir).forEach((pathname) => {
    let fullPathName = path.resolve(pageDir, pathname);
    let stat = fs.statSync(fullPathName);
    let fileName = path.resolve(fullPathName, mainFile);

    if (stat.isDirectory() && fs.existsSync(fileName)) {
      entryMap[pathname] = fileName;
    }
  });

  return entryMap;

}

const entryMap = getEntry();
const htmlArray = getHtmlArray(entryMap);

module.exports = {
  mode: 'development',
  devServer: {
    contentBase: devPath,
    hot: true
  },
  entry: entryMap,
  resolve: {
    alias: {
      components: path.resolve(srcRoot, 'components')
    },
    extensions: ['.js', '.jsx']
  },
  output: {
    path: devPath,
    filename: '[name].min.js'
  },
  module: {
    rules: [
      { test: /\.(js|jsx)$/, use: [{ loader: 'babel-loader' }, { loader: 'eslint-loader' }], include: srcRoot },
      { test: /\.css$/, use: ['style-loader', { 'loader': 'css-loader', options: { minimize: true } }], include: srcRoot },
      {
        test: /\.scss$/, use: ['style-loader', 'css-loader', 'sass-loader', {
          loader: 'sass-resources-loader',
          options: {
            resources: srcRoot + '/components/common.scss'
          }
        }], include: srcRoot
      },
      { test: /\.(png|jpg|jpeg)$/, use: 'url-loader?limit=8192', include: srcRoot }
    ]
  },
  optimization: {
    splitChunks: {
      cacheGroups: {
        common: {
          test: /[\\/]node_modules[\\/]/,
          chunks: 'all',
          name: 'common'
        }
      }
    }
  },
  plugins: [
    new webpack.NamedModulesPlugin(),
    new webpack.HotModuleReplacementPlugin(),
    new MiniCssExtractPlugin({
      filename: "[name].css",
      chunkFilename: "[id].css"
    })
  ].concat(htmlArray)
};
